through games of 1/7/10

The S&P+ Ratings are a college football ratings system derived from the play-by-play and drive data of all 800+ of a season's FBS college football games (and 140,000+ plays).
The components for S&P+ reflect opponent-adjusted components of four of what Bill Connelly has deemed the Five Factors of college football: efficiency, explosiveness, field position, and finishing drives. (A fifth factor, turnovers, is informed marginally by sack rates, the only quality-based statistic that has a consistent relationship with turnover margins.)
Here are the components of the ratings shared below:

Second-Order Wins (2ndO Wins): Defined here and discussed in further detail here and here, second-order wins compare the advanced statistical components of a given game, and the single-game win expectancy they create, to the actual results of the game. This projected win total is a cousin of the Pythagorean record, a concept common in many sports. They are presented below, with the difference between a team's wins and second-order wins in parentheses.

S&P+ rating: Using the five-factors concept above, the S&P+ ratings take into account efficiency (Success Rates), explosiveness (IsoPPP), and factors related to field position and finishing drives. It is now presented in two forms: the first is a percentile, and the second is an adjusted scoring margin specific for this specific season's scoring curve.

Off. S&P+ rating: A team's offense-specific S&P+ rating, presented in the form of an adjusted scoring average.

Def. S&P+ rating: A team's defense-specific S&P+ rating, presented in the form of an adjusted scoring average (and since this is defense, the lower the average, the better).

Strength of Schedule rating (SOS): A simple schedule measure based on average S&P+ ratings and normal distributions.

Weighted S&P+ rating: This is an attempt to measure how a team was playing at the end of a given season, with extra weight given to the most recent games. It is limited in power by small sample sizes, but it is useful in determining which teams finished strong and which derived most of their good (or bad) final ratings from early-season play.

Use the menu above for pages that give more details on offensive and defensive S&P+, or our other college football ratings, the drive-based FEI.